Circuit-breaker contact.



v No. 896,764. PATENTED AUG. 25, 1908.

W. M. SOQTT & H. C. GAMPION, JR. GIRCUIT- BREAKER CONTACT'.

A?PLI'0ATION FILED JAN, 30, 1906.

' the line A-B in Fig. 3.

UNITED sTATEs PATENT oEEIcE.

WILLIAM M. SCOTT AND. HARRY CLIFFORD CAMPION, JR., OF PHILADELPHIA,4 PENNSYLVANIA; SAID CAMPION ASSIGNOR TO SAID SCOTT. i

CIRGUIT-BREAKER CONTACT.

Specification of Letters Patent.

Patented Aug. 25, 1908.

ApplicationiledvJanuary 30, 1906. Serial No. `298,611.

To all whom 'it may conce-m:

Be it known that we, WILLIAM M. Sco'rr lieve the main contacts of the detrimental.

effects of arcing incident to the rupture of a circuit carrying an electrical curient, especially when the current is of high voltage orpower.

It is the object of our invention to produce a supplemental, or shunt contact piece, usually of carbon, which shall be practically nonbreakable under usual. working conditions. It has been found that the carbon shunt contact pieces commonly employed are subject to breakage eitherat the time they are being assembled in the switch or circuit breaker, or when in service, and especially in the latter case withJ regard. to the movable carbon which is subjected to considerable inertia effects. To this end we reinforce or strengthen the carbon shunt contact pieces by applying thereto a metal or other coating, electrolyt-ically orV otherwise applied, which greatly strengthens the contact pieces and enables them to withstand any mechanical strainsthey are likely to be subjected to.l

For an illustration of our invention reference is to be had to, the accompanying drawings, in which Figure 1 is a side elevational view of an automatic circuit breaker employing our reinforced carbon shunt contact pieces. Fig. 2 is an enlarged side elevation of thc stationary shunt carbon reinforced according to our invention. Fig. 3 is a front elevational view of the shunt contact piece shown in Fig. 2. Fig. 4 is a vertical sectional view taken on Fig. 5 is a sectional view taken on the line C--D in Fig. S. Fig. 6 is an enlarged view showing a side elevation of the movable shunt carbon reinforced according to' our .'ii sentieri.

In Fig. 1, B is a base of marble or other Suitable insulating material on which are mounted the main copper terminal blocks 1 and 2 adapted to be bridged by the laminated bridging member 3 secured to the arm 4 whichis pivoted at 5. The toggle 6, 7is adapted to crainp the laminated contact member 3 into engagement with the termif nal blocks 1 and 2, the operating handle 8 being integral with the toggle link 7. A latch 9 serves to lock the 4parts in circuit closing position and electro-magnetic tripping means serve to actuate the latch in a manner well understood in this art.

The arm 4 has an. upwardly projecting portion 10 to which are mechanically'secured but from which are electrically insulated the movable metallic shunt contact piece 11, spring supported, and the movable carbon shunt contact iece 12, the latter pivoted at 13. The metalic shunt contact 11 coperates with the metallic plate 14 forming a part' of the bracket 15 secured and in electrical contact with the upper main terminal block 1. The movable carbon 12 coperates with the stationary shunt carbopi 16 pivoted in the bracket 15 at 17.

As well understood in the art, when the circuit breaker is tripped or opened, the laminated contact member 3, separates from the main contact terminals 1 and 2, thereafter the metal contact 11 separates lfrom the carbon 16, and thereafter the carbon contact 12 separates from the carbon contact 16, and it is at these carbons that the final arcingoccurs.

Referring to Figs. 2 to 5 inclusive, a groove 18 is made along the two sides, across the bottom, and across the flat face of the carbon 16, thus forming a continuous channel.

The portion of the surface of the carbon which is to remain exposed, is covered with paraffin or other easily removable insulating material up to the` edge of the continuous groove 18.' The groove 18 is in effect the boundary or limit of the portion of the carbon which is to remain exposed. The rcmainder of the carbon is not coated with parafhn. The carbon is then placed in an electro-plating bath, and copper, or'any other suitable material, is plated on to it, covering all the parts not treated with paraffin. lVhen the electro-plate coating has reached a suitable thickness, the'- carbon is removed and the paraffin is removed from its surface thus leaving an effectively reinfcrced and strengthv'ened carbon contact. 4This coating is 'represented at 19 throughout the drawings.

.holes 21 andare screw threaded into t e pivoted-meinbers 2 2. As shown the metallic reinforcing plate. extends over the walls of `the holes 2l and over the bottoms of the depressions 20. The coating over the portion o f the youter surface of the carbon, and extendingas wellA into the body of the carbon,

by covering the surfaces of the holes 21 and the bottoms of the depressions 20, produces a greatly strengthened and materially irnproved carbon shunt contact piece for electric switches or circuit breakers.

It has been found that carbons reinforced according to our invention withstand great mechanical shocks and strains which heretofore caused breakage of carbon shunt contacts.

We are aware that carbon or graphite coml mutator brushes have been copper plated for' the purpose of securing eflicient electrical contact between the brushes andv their brush holders, where relative movement generally occurs. We are also aware that arc light carbons have been electro-plated with copper for the purpose of reducing their resistance.

We accordingly do not clalrn plated carbonor graphite, or plated brushes or arc light carbons, but confine our invention to reinforced shunt contact pieces of carbon or like material.

l/Vc reinforce our carbons and do not apply a conducting coating over their entire outer surfaces as is customary with dynamobrushes. While our coating increases the conductivity, it is incidental, for in shunt contacts rit 1s not an object to reduce resistance or increase conductivity. It is our object to mechanically reinforce the carbon so that it may successfully withstand the shocks and strainsl to which itis subjected.

What we claim is:

1. In an electrical switch, a shunt contact piece, a groove in the surface thereof, and a -reinforcing electroplate applied to said surface and extending in to said groove.

2. In an electrical switch, a carbon shunt contact piece, a groove in the surface thereof dividing said surface into active and nonactive portions, and a reinforcing electroplate applied to the inactive portion and extending into said groove.

3. In'an electricallswitch, a carbon shunt contact plece, an aperture therein to receive dent to assemb fastening means,fand a reinforcing vcoatin electro-plated upon the .externaly surface o said'pie'ce and upon the wall of said aperture. 4. Inan electrical switch, a carbon shunt contact piece, and a reinforcing electro-plate extending into the body-and covering 'a por; tion of the surface thereof.

5. In an electrical switch, a carbon shunt contactpie'ce, a groove in the surface thereof, and a reinforcing electro-plate applied to said surface and extendin' to said groove.

6. In an electricaI. switch, a refractory shunt Contact piece having arcingA and nonarcing surfaces, a groove dividing the surface of said piece into arcin and non-arcing portions, and a mechanicay reinforcing electroplate coating applied to the non-arcing por tion ofthe surface of said piece, whereby said shunt contact piece vresists the strains inciy and switch operation.

7. In an electrical switch, `a carbon shunt contact piece,an a erture extending therethrou h to receive astening means, a countersin and an electro-plate coatincp applied to a portion of the surface of said contact piece and to the walls of saidaperture and countersink.

8. In an electrical switch, a carbon shunt contact piece, av groove in. each of a-plurality of faces of said piece and dividing thetsurface of said piece into arcin and nQn-arcing portions, and a mechanicay reinforcing electroplate applied to the non-arcing portion.

9. In an electrical switch, cooperating shunt carbon pieces adapted to engage each other, a groove on each carbon dividing the surface of the same into engaging and nonengaging portions, and a reinforcing electroplate on the non-engaging surface yof each carbon and extendin to said groove.

' 10. In an electricaswitch, a Vcarbon shunt contact piece, an aperture therein ada tedto receive as electro-plate u, on the wall of said aperture.

11. In an eectrical switch, a composite shunt contact piece consisting of refractoryv conducting material and a relnforcing electro late, said electroplate covering a portion WILLIAM M. SCOTT. HARRY CLIFFORD CMPION, JR.

Witnesses: JAMES H. BELL, ALICE S. MARSH.

roo

tening means, .andy a rein orcing 

